75 



The Enzymes Concerned in the Decomposition of Glucose and 

 Mannitol hy Bacillus coli communis. Part II. — Experiments 

 of Short Dwation with an Emulsion of the Organisms/^ 

 By Egerton Charles Grey (Beit Memorial Eesearch Fellow). 



(Communicated by Dr. A. Harden, F.R.S. Received July 25, 1917.) 

 (From the Laboi'atoiy of Prof. A. Fernbach, Institut Pasteur, Paris.) 



CONTENTS. 



PAGE 



Bacteriological Technique • 76 



Apparatus for the Study of a Complete Fermentation 77 



Chemical Technique 80 



The Fermentation of Glucose in the Presence of Chalk by an Emulsion 



of B. coli convimmis S3 



The Comparison between the Products from Glucose and those from 



Mannitol 89 



Summary and Conclusions of Part II 91 



The earlier experiments described by the writer upon the decomposition of 

 glucose and mannitol by B. coli communis^ were open to the objection from 

 the biological side that no attempt was made to distinguish those products 

 which arose by enzyme action from those which might be more particularly 

 associated in their formation with the growth and multiplication of the cells, 

 and from the chemical side that certain substances of unknown composition, 

 such as peptone, were employed, so that it was not possible to be sure that 

 some of the products of fermentation had not been derived from this source. 



To overcome these objections the author has adopted a new plan of \York 

 which aims at separating the process of growth from that of fermentation. 



The method consists in growing the bacteria upon a suitable medium and 

 adding them when sufficiently developed to a solution of the substance to be 

 fermented. The bacteria are washed from the surface of the medium by means 

 of a solution of potassium sulphate, and the emulsion so obtained is added 

 to the substance to be fermented, in the presence of chalk. Under such 

 circumstances an amount of bacteria which would weigh, when dry, 1 grm. 

 will, in the case of B. coli commitnis, bring about the degradation of 40 grm. 

 of glucose in 48 hours. 



A period of 48 hours is too long for the fermentation if it be desired to 

 study the separate phases of the fermentation process, nevertheless, in 



* Part I of this work appeared in these Proceedings, B, vol. 87, p. 472 (1914). 

 t Grey, E. C, ' Eoy. See. Proc.,' B, vol. 87, p. 472 (1914). 

 VOL. XC. — B. H 



